The invention relates to a magnetic tape cartridge and more particularly relates, in a magnetic tape cartridge for rotatably housing within a cartridge case a single reel having magnetic tape wound thereon, to the structure of reel-rotation restraining means for causing the reel to be in a rotation-restrained state when not being used.
In conventional tape cartridges used as storage media that are employed in external storage units for computers, etc., there is known a type in which magnetic tape is wound on a single reel and this reel is rotatably housed within a cartridge case. This magnetic tape is employed as a data storing tape for computers, etc., and because important information is stored, reel-rotation restraining means to restrict rotation of the reel is installed so that problems, such as tape jamming, etc., do not occur and so that the magnetic tape is not forwarded unexpectedly when not being used, such as when being archived, etc.
The reel-rotation restraining means is equipped with a restraining member that restricts rotation of the reel by engaging part of the reel, and is provided so that when the cartridge is loaded into a drive unit such as an external storage unit, etc., a restrained state by the restraining member is released according to a reel chucking operation performed by drive-side rotation drive means.
Hence, due to demands for enhancement in the reliability of the aforementioned operation of the reel-rotation restraining means, prevention of dust entry into the cartridge, etc., this reel-rotation restraining means is provided in a structure separated into a restraining member for restricting rotation of the reel, an urging member for urging this restraining member in a restraining direction, and a releasing member for moving the restraining member in a releasing direction by moving in accordance with the chucking operation of the drive-side rotation drive means.
That is, in the non-operative condition, the reel is restricted by the restraining member so that it does not rotate unexpectedly, as a result of which the magnetic tape is not forwarded. However, if the cartridge is loaded into a drive unit and chucking of the reel is performed by rotation drive means, the releasing member moves in interlock with the chucking operation and releases the restraining member. In this state, the reel is rotatable and therefore the magnetic tape can be forwarded and rewound.
In the aforementioned mechanism, it is also preferable to perform the pushing-operation, for the releasing movement of the releasing member which results from the chucking operation of the drive-side rotation drive means, at a plurality of positions on the outer peripheral portion rather than at a single position on the center portion, because a stable releasing operation can thus be performed. At this time, it is advantageous in achieving structural simplification, etc., to provide a reel gear, which meshes the driving gear of the drive-side rotation drive means, in the reel, to provide pushing-up portions, formed in part of the releasing member, so that the distal ends abut the driving gear through the through holes provided in the real gear, and to provide the driving gear so that when the drive-side rotation drive means performs the chucking operation, the driving gear pushes the pushing-up portions and releases the releasing member.
However, piercing the reel gear and boring the through holes, as described above, will reduce the mesh between the reel gear and the driving gear and therefore become a problem with respect to driving the reel reliably. If the through hole is reduced from such a respect, the shape of the portion of the releasing member inserted into this through hole will also become smaller and therefore there is a possibility that it will become unstable for the tooth edge of the driving gear to abut the reduced portion accurately and give a reliable pushing operation.
In addition, in the case where the pushing-up portions are formed in part of the releasing member and are inserted into the through holes of the reel and slid, as described above, the releasing member is subjected to the urging force of the urging member and gives rise to bending deformation. As a result, since a tilting force acts on the push-up portion, part of the outside surface is pushed against the inner surface of the through hole and the friction resistance becomes greater, the sliding between the pushing-up portion and the through hole is disturbed, and there is a possibility that the releasing member will not be able to release the restraining member reliably.
The present invention has been made in view of the above-mentioned points, and accordingly, the object of the invention is to provide a magnetic tape cartridge in which the releasing member of the reel-rotation restraining means is capable of performing a reliable releasing operation.
To solve the aforementioned problems, there is provided a magnetic tape cartridge, for rotatably housing within a cartridge case a single reel having magnetic tape wound thereon, comprising reel-rotation restraining means for allowing rotation of the reel when being used and restricting the rotation when not being used; wherein
the reel-rotation restraining means has a restraining member for restricting rotation of the reel by moving toward or away from the reel, an urging member for urging the restraining member in a restraining direction, and a releasing member for moving the restraining member in a releasing direction, by rotating integrally with the reel and moving according to chucking operation of drive-side rotation drive means;
the reel is provided with a reel gear which meshes a driving gear of the drive-side rotation drive means, and a pushing-up portion formed in part of the releasing member is provided so that a distal end thereof can abut the driving gear through a through hole provided in the reel gear; and
the through hole is bored between tooth edges of the reel gear.
Also, it is preferable that a recess engageable with a tooth edge of the driving gear be formed in a distal end surface of the releasing member which abuts the driving gear.
According to a magnetic tape cartridge such as the aforementioned, the through hole which is provided in the reel gear of the reel-rotation restraining means is formed between the tooth edges of the reel gear. Therefore, even if the through hole is small, the tooth edge of the driving gear which meshes the reel gear can reliably abut the pushing-up portion of the releasing member projecting through the through hole and push the pushing-up portion. Since the movement of the releasing member can be stably performed, the restraining member can be reliably released with a predetermined amount of movement, and the operational reliability of the reel-rotation restraining means can be assured.
In addition, in another magnetic tape cartridge of the present invention, the reel is provided with a reel gear which meshes the driving gear of the drive-side rotation drive means, and a pushing-up portion formed in part of the releasing member is provided so that a distal end thereof can abut the driving gear through a through hole provided in the reel gear. The pushing-up portion and the through hole are brought into contact with each other through small protrusions which reduce the contact area.
According to a magnetic tape cartridge such as the aforementioned, the pushing-up portion provided in the releasing member of the reel-rotation restraining means, and the through hole provided in the reel, are brought into contact with each other through small protrusions which reduce the contact area. As a result, the friction resistance between the two is reduced, and even if bending deformation develops in the releasing member, movement of the pushing-up portions can be stably performed according to the chucking operation of the drive-side rotation drive means. In addition, the restraining member can be reliably released with a predetermined amount of movement, and movement to the restrained state can also be assured. Thus, the operational reliability of the reel-rotation restraining means can be assured.
In a preferred form of the magnetic tape cartridge, the opposite tooth edges of the reel gear between which the through hole is bored are removed so that they become flat shapes, curved surface shapes, or chambered surface shapes.
Another magnetic tape cartridge is characterized in that the releasing member is formed by pressing of a metal sheet.
Still another magnetic tape cartridge is characterized in that the reel is provided with a guide member which guides part of the releasing member in an inserting direction when inserting the pushing-up portion of the releasing member into the through hole.
A further magnetic tape cartridge is characterized in that the pushing-up portion of the releasing member is provided near each vertex of a generally triangular plate base. In a preferred form of this magnetic tape cartridge, the plate base of the releasing member is formed integrally with the pushing-up portion with high-rigidity resin material, while a sliding-contact portion, formed with a separate member having a low friction characteristic, is rigidly attached integrally to a center portion of an upper surface of the base which comes into contact with a center portion of a lower surface of the restraining member.
Another magnetic tape cartridge is characterized in that gate traces for injection molding are provided near centers of rotation of the restraining member and the releasing member. In a preferred form of this magnetic tape cartridge, in the releasing member which has the pushing-up portion and is formed by injection molding, such a bore which reduces a wall thickness of the pushing-up portion is formed in the interior of the pushing-up portion.
Still another magnetic tape cartridge is characterized in that the reel gear is driven to rotate in mesh with a driving gear in which a tooth edge portion thereof is formed into a curved surface.
A further magnetic tape cartridge is characterized in that a tooth edge portion of the reel gear is formed into a curved surface.
Another magnetic tape cartridge is characterized in that the reel is formed by molding a metal reel plate on a bottom surface thereof by insert molding, and the reel is molded by a metal mold in which a hold member for holding an inner peripheral surface of the reel plate is disposed on an outer periphery of a gate.
Still another magnetic tape cartridge is characterized in that the reel is formed by molding a metal reel plate on the inner peripheral side of the reel gear by insert molding, and the reel is molded by a metal mold provided with a means of preventing interference between a gear-portion metal mold for molding the reel gear and the reel plate.
A further magnetic tape cartridge is characterized in that the reel is formed by molding a metal reel plate by insert molding and in that the reel is formed so that outside the outer peripheral surface of the reel plate, a clearance in the form of a circumferential groove is formed between the outer peripheral surface and a bottom wall of the reel, and so that outside the clearance, the reel gear is formed.
Another magnetic tape cartridge is characterized in that the reel is formed by molding a metal reel plate by insert molding and in that the reel is formed so that a reinforcement rib is formed on a surface of the reel plate which contacts a bottom wall of the reel.
Still another magnetic tape cartridge is characterized in that the reel is formed by molding a metal reel plate by insert molding and in that the reel is formed so that a recess is formed in a bottom wall of the reel which the reel plate contacts.
A further magnetic tape cartridge is characterized in that the reel is formed by joining a reel hub and an upper flange portion by adhesion, and in that the reel is formed so that the upper flange portion is provided with a collar portion which fits onto an inner peripheral surface of the reel hub, an annular protruding portion is formed between the collar portion and a surface of the upper flange portion, and so that an end surface of the annular protruding portion and an outer peripheral surface of the collar portion are adhered to the reel hub as adhesion surfaces.